Tiny Diamond Sensor Measures Heart’s Magnetic Field at Room Temperature
Physicists at Johannes Gutenberg University Mainz built a fiber-based instrument around a sub-0.5-cubic-millimeter diamond to detect magnetic signals from the heart. The approach uses magnetocardiography, which avoids skin electrodes and is less affected by tissue conductivity than ECG. Although current diamond sensors remain less sensitive than SQUID and OPM systems, their room-temperature operation could make magnetic heart mapping more practical, the researchers report in Science Advances.
Nitrogen-vacancy centers are atomic defects in diamond: a nitrogen atom substitutes for carbon, leaving an adjacent empty lattice site. Their energy levels allow precise sensing of magnetic fields, temperature, and mechanical stress. The Mainz device uses a truncated pyramid diamond smaller than half a cubic millimeter, enabling room-temperature operation and direct skin placement.
Magnetocardiography records the heart’s magnetic activity without skin electrodes, and tissue conductivity has little effect. Existing SQUID and optically pumped magnetometer systems still offer better sensitivity and noise discrimination. The work, part of the DIAQNOS project, compared three independently developed sensors and appeared in Science Advances.
If diamond magnetometers improve, patients with burns or other barriers to electrode placement could benefit from contact-free heart mapping. Clinicians may gain a portable, room-temperature option for detailed cardiac and neural measurements, potentially reducing reliance on cryogenic equipment. Researchers and device makers could see new pathways for biomedical quantum sensing. Yet current sensitivity limits mean near-term impact may remain in labs and specialized settings rather than routine care.